Clive Palmer claims his company Queensland Nickel has now paid its outstanding carbon tax bill, after reports of his looming multimillion-dollar debts.

But Queensland Nickel's apparent payment of $6.8 million - Mr Palmer made the claim on Twitter on Tuesday - would still fall short of its tax obligations, according to the Clean Energy Regulator, the agency that collects carbon tax payments.

Mr Palmer, the federal MP for the Queensland seat of Fairfax and leader of the Palmer United Party, appears eager to neutralise the story about his carbon debt before this weekend's re-run of the West Australian Senate Election.

But the issue is unlikely to disappear, with the Clean Energy Regulator confirming Mr Palmer's Queensland Nickel owes the government $8.44 million in its 2012-13 carbon tax liabilities. Not only that, the nickel refinery owes a further $1 million in late penalties accrued by March 27, leaving a total debt so far of about $9.5 million, the regulator said.

Advertisement

"The Clean Energy Regulator is currently investigating whether Queensland Nickel Pty Ltd has made any payments towards the debt in the last 24 hours," a spokeswoman for the Clean Energy Regulator said.

"We have no record of payment having been received at this stage".

Shortly after noon on Thursday, Mr Palmer tweeted: "Qld Nickel's $6.8M Carbon Tax bill paid today before due date of April 5 as requested by the Clean Energy Regulator".

But about half an hour before his tweet, Mr Palmer told Fairfax Media in a phone conversation that he did not know how much money had been paid, only that it was "millions of dollars" and it had been "authorised weeks ago".

"I just checked with the company [Queensland Nickel] half an hour ago," Mr Palmer said. "They said it had been authorised by the bank and was going through … It should be through inthree hours though it's all electronic you know."

Mr Palmer is campaigning to win his political party a third Senate seat in West Australia.

He continues to face conflict-of-interest questions over his company's unpaid carbon tax bill, given Mr Palmer has argued for the Abbott government to make its repeal of the carbon tax retrospective.

This would absolve Mr Palmer's North Queensland nickel refinery of its carbon tax bill owed to the Clean Energy Regulator.

Prime Minister Tony Abbott has insisted that Mr Palmer should respect the law and that his company should pay its outstanding taxes.

Mr Palmer claimed Tuesday's story on the front page of The Australian reporting on his unpaid taxes was a conspiracy between the Abbott government and Rupert Murdoch to deny him a Senate seat in Western Australia.

"Why did they bring this up this week?" Mr Palmer said. "Why is the government, ministers and the departments handing stuff to Rupert Murdoch?"

Mr Palmer offered no evidence for this theory. He said he still believed the carbon tax was an "illegal tax" and he still planned to follow through on a High Court challenge to declare the tax unconstitutional.

Mr Palmer claimed his company, Queensland Nickel, had received an extension on its deadline to pay its carbon tax bills, and that the money did not need to be paid until April 5. Tuesday's apparent payment, he argued, was therefore an early payment.